This adapter make you attach your video camera with a 'C' or 'CS' thread to your telescope for prime focus photography. C-threads are commonly used in most consumer video cameras whereas the CS thread is mostly used in security cameras. The camera must have a standard removable C-mount lens, which is a 1" diameter thread. Will not work on video cameras with a fixed lenses or bayonet mount. Useway: attach the camera to the C-thread of this adapter. Then slide the 1.25" barrel into your 1.25" telescope focuser and you are ready to shoot. Internally grooved to reduce stray light reflection for maximum contrast Features: Internally grooved to reduce stray light reflection for maximum contrast Made of black anodized aluminum Camera/Camcorder Fitting: C-Mount Lens Fitting: 1.25" telescope lens Type: Lens Adapters Model: 1.25" telescope lens Total Length: 30mm